cmd: mem: Show 64bit addresses which are tested

Fix print message to show full 64bit addresses.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/cmd/mem.c b/cmd/mem.c
index efa3929..a690957 100644
--- a/cmd/mem.c
+++ b/cmd/mem.c
@@ -1038,7 +1038,7 @@
 		return -1;
 	}
 
-	printf("Testing %08x ... %08x:\n", (uint)start, (uint)end);
+	printf("Testing %08lx ... %08lx:\n", start, end);
 	debug("%s:%d: start %#08lx end %#08lx\n", __func__, __LINE__,
 	      start, end);